Gas discharge relay



Aug. 4, 1936.

H. H. GEFFCKEN ET AL GAS DISCHARGE RELAY Filed Oct. 15, 1952 Fig.1

ATTORNEY Patented Aug. 4,- 1936 GAB DI Enemy Heinrich H. Geii'cken and Hans B. Richter, Ileipaig, Germany, assignors. by mesne assignments, to Radio Corporation at America, a corporation ofDelaware s pumao i omw 15,1532. sci-m No. esaozs rent and decreasing the operating potential and the losses incurred in the tu v These tubes known asgrid glow tubes, are used extensively for power controlling and relay purposes in both the signalling and power fields.

The essential dififerences of gaseous discharge relays of the above described type as comred with the usual electronic discharge tubes operating with a high vacuum as used. extensively in the radiov and allied arts, reside in the control or ignition electrode. In the case of vacuum tubes, the control electrode is eiiective during the entire duration of the discharge; in the c of'gaseous discharge relays,'the control electrode controls the starting of the discharge only without exerting any further influenceupon the discharge, once it has been started. During e discharge interval, the control or ition electrode assumes an average ireepotential determined by the discharge current.

In order to provide a continuous and quantitative control of. a gaseous discharge relay in accordance with input potentialvariations applied to the control or ignition electrode s to the operation 01' electron tubes, it is necessary torinterrupt the anode or output circuit of negative biasing potential or the control elec-' trode, which condition, is characterized by a substantially complete ireedom'irom ionizationoithe discharge space.

should be regarded as illustrative 'only of the According toa well known g ltB ini-. tial condition relative to the tree potential or a- October 1c, 1931 ((31; 250-415) Our invention relates to gaseous discharge de- One object of our invention is to provide means including novel -circuit connections for eiiecting a quantitative control 0! the discharge current 0! a gas discharge relay device in accordance with a varying input potential .ims pressed upon the control electrode. 7

Another object of our invention consists in the provision of a gaseous discharge relay with means including novel circuit connections whereby periodic discharge periods are obtained 10 of substantially equal duration and a frequency dependent on the value of the varying input control potential.

Another object 01' our invention is to provide a novel circuit for gaseous discharge relay or it accurately timing the starting/oi the discharge in accordance with a varying input control potential.

Still a iurther' object of our invention is to provide a, circuit for opera a gaseous diso charge relay for securing a continuous and grad ual control of the discharge output current in accordance with input i; variations independent oi the use oi either an alternating. or direct currentope'rating voltage. 25 Another object of our invention is to provide a novel control circuit for gaseous discharge relays adapted for frequency reduction.-

. l--. objects and novel aspects oi theinveion will appear from the following detailed 39 description wherein we have set forth several preferred embodiments of our invention; We

wish it to be understood, however, that the.

description inconnection with the drawing- 35 broader and underlying principles of the invention which, as will become obvious, is subject to many variations and modifications coming wi the broadest scope and spirit of the invention, as expressed in the appended claims.

1 1 illustrates a novel circuit arrangement in accordance with the invention for aifordlng a quantitative control of the output current of a gaseous discharge relay utilizing an oscillatory circuit to react onthe discharge device Ior producing a discharge t rw. potential on the control electrode. Figure 2 illustrates another embodiment ci the invention utilizing a saturated iron core transformer for securing properly timed control Figure 3 illustrates a number of illustrative, curves explanatory of the operation of the circuit according to Figure 2.

Figure 4', by way oi example, illustrates one as the automatic operation of .a railroad crom-bar.

' tion of a photoelectric device or the like.

Similar reference numbers denote similar parts throughout'the different views of the drawing.

The invention, as mentioned, relates to a novel method of operating gaseous discharge .relays, preferably of the incandescent cathode type. Principally the invention contemplates the provision of means for applying a negative charge to the grid of a gas discharge device prior to the starting of the discharge and means for consecutively allowing said charge to leak of! during a time period varying in accordance with a variable input condition until reaching a value sufficient to efiect the starting. or restarting of-the discharge through thetube. For instance,

in an arrangement in which the discharge is effected periodically, such as by the use of an alternating current anode potential, a positive charge may be applied to a condenser connected to the grid through immediately prior to the positive or operating cycles of the anode voltage, which charge is then allowed to leak of! through a variable. input impedance, such as a photoelectric cell, variable resistance -or the like, whereby varying discharge periods are secured, resulting in current impulses of varying duration through the output circuit of the tube. In this manner the average current flow through the output circuit may be quantitively and continuously controlled in accordance with the variation of an input condition, such as the illumina- This method afiords a greatly simplified circuit and besides, involves a number of unexpected novel eifects adapted to increase to a large extent the practical uses of such discharge devices.

' Referring now more particularly toFigure 1 of the drawing, we have shown at I, a gas discharge device comprised of an incandescent cathode 2, anode 3, and a control electrode 4 surrounding the cathode. The discharge device I is supplied with operating energy from a direct current potential source, indicated by .the plus and minus signs in the drawing, through a filter comprised of series chokes 5, 6, l, 8, and parallel condensers 9 and Ill. Furthermore, a series oscillatory circuit comprised of a condenser II and inductance coil I2 is connected in parallel to the discharge device I, as shown. The ignition electrode or grid 4 is coupled through a condenser I3 and coupling coil II with e circuit II-I2 and is furthermore connected t the positive pole of the potential source through a photoelectric cell or any other control device, such as high .ohmic resistance, etc. An instrument I6 or other translating device is provided for measuring the direct current flowing through the system. The filter 5-I Il may be omitted and a counting device substituted for the instrument IS. The heating circuit of the incandescent cathode 2 has not been shown for the sake of simplicity as being unnecessary for. the proper understanding of the operation of the invention; it is necessary that the heating circuit is always closed some time before the closing of the switch I! which serves for putting the system into operation.

The operation of the system as shown by Figure 1 is as follows: when the switch I! is closed,- the tube I is ignited and a discharge started. Condenser II which has previously been charged to the full operating potential is then discharged through the tube in the form of an oscillatory discharge. Considering the negative or electron reversal of the condenser potential, the plate 3 current flow of this discharge, it is seen that the electrons accumulated on the lower plate of condenser due to the negative charge thereon, will flow through the coil I2 and the tube I to the upper or positive plate, thus establishing a 5 discharge current. Due to the electro-magnetic inertia of the self-inductance coil I2, more discharge current will flow through the circuit than would be necessary to just neutralize the positi've and negative condenser charges, as is well understood in accordance with the theory of electric circuits, resulting in a temporary reversal of the polarity of thecharges on the condenser; that is, the upper plate will temporarily become negative and the lower plate positive due to the further action of the choke coils 5, 6, I, 8 of the filter circuit which prevent the oscillatory discharge current from entering the remaining circuit portions of the system. By the temporary 20 of the device I will become negative for a short period relative to its cathode 2, thus stopping or extinguishing the discharge through the tube and restoring the original condition, whereupon the same phenomena will take place in periodic 25 succession, as is well understood.

During the-oscillatory discharge, a potential impulse has been applied to the grid circuit through the condenser I3 and by means of the induction coil It in coupling relationship with 30 the coil I2. By proper arrangement of the polarity of coil I4, the right hand plate of the condenser I3 is made positive, resulting in a corresponding negative potential being established on the left hand plate connected to the 35 grid 4. The necessary electrons for the negative potential are attracted from the emission current through the tube supplied by the cathode I.

In order to secure proper phase adjustment, a condenser I4 is arranged in parallel with the 40 inductance coil I4. During the above operation, as pointed out, electrons are trapped on the plate of the condenser I3 connected to the control electrode 4. These electrons are attracted by the control electrode from the discharge emission 45 of the cathode 2, but will, however, flow back to the ignition electrode as soon as the induced voltage impulse produced in the induction coil I4 begins to assume a negative value. These electrons thus produce a negative charge on the 50 .energy also known as audion detector eil'ect.

While in the latter the charges are continuously applied'to-the grid and carried away by the leak 05 resistance, in the case of the invention periodic impulse charges are applied at definite time interyals for determining the re-starting time of the gas discharge during periodic operating cycles in accordance with the novel purpose and 7 function of the system according to the invention. In this manner, periodic discharge currents will flow thrpugli the discharge tube I having a frequency, dependent on and substantially proportional to the illumination of the discharge, a negative potential impulse is applied to the ignition electrode 4. For this purpose, as is obvious, both oscillatory circuits or contact devices could be provided.

Referring now to Figure 2, we have shown another embodiment of our invention in which an alternating operating current is used for operating. the discharge device. The discharge tube l8 has an incandescent cathode l9 which, in the same manner as in the case of Figure 1, is preferablyoi the indirect heater type, an anode 20 and an ignition or control electrode 2|. A load impedance 22 is included in the main circuit as shown. A small transformer 24 supplied from an alternating current source indicated at 23 and having a highly saturated iron core, has one 01' its secondary terminals connected to the ignition electrode 2i through the condenser 25, the other terminal being connected to the cathode It. The ignition electrode 2| is furthermore conby the secondary of the transformer 25; andcurve 39 represents the potential of the control electrode 2|. A discharge will be produced through the tube during the period, as indicated by the cross-hatched area in the diagram.

The transformer 2c is designed in such a manner that its core becomes fully saturated with very low instantaneous values of the alternating supply current such as at about 8 to 10 volts in case of a 110 volt supply source. In this manner, steep voltage peaks are pro duced in the secondary and applied to the condenser 25.

At the nning of each alternation d which the incandescent cathode i9 is negative, a positive potential impulse is applied to the lower plate of the condenser 25 provided the polarity or winding sense of the secondary 2c is properly chosen. Due tothis positive potential, a corresponding negative potential is induced on the upper plate of condenser 25 whereby the required negative electrons are absorbed by the control electrode 2! from the discharge current-oi the tube and accumulated on the condenser}! in a manner similar as described in connection with Figure l. with decreasing transformer voltage or cessation of the impulse. voltage as shown at It inFigure-il, the electrons on theupper plate of condenser 25 will-return to the ignition electrode, thus producing a highnegative charge thereon, such as shown by the curve SI in Figure 3. This charge will then leak of! through the photoelectric cell 26. The discharge brahch 'a high ohmicresistance.

, uously controlled.

of the potential curve 30 approaching the abscissa axis. will be more orless steep, dependent on the intensity of the current or impedance ot the photoelectric cell 26. Aswill be understood the discharge will be -started atthe point of intersection of the critical potential curve 28 and the falling branch of the curve 3!! representing the charging and discharging potential.

In this manner, as is seen, the starting of the discharge during the periodically recurring positive-cr operating cycles of the tube after the grid has re-gained its control may be accurately timed in accordance with variations of a physical characteristic to be controlled, such as'varying illumination of an input .photoelectric cell as shown resulting in a corresponding variation of the integrated or average current flow through the tube as described.

One advantage, among others, of a system and method for controlling gaseous discharge tubes according to the invention over-the aforemene tioned phase controlmethod known in the art -is due to the fact that the operation is substantially independent of slight variations of the capacity of the grid condenser caused by atmosslight capacity variations will cause subtantial interference with the proper operation, as is obvious.

A further advantage of the invention resides in thefact that it is possible, by means of an arrangement just described, to extend. the control over a greater number of alternations of the supply voltage. For this purpose it is only necessary to design the circuit in such a manner that prior to the setting in of the, discharge, a very steep positive hall wave is applied to the transformer 25, as illustrated in'Figure 3, in-such a manner to prevent a rel-starting of the discharge during several alternations of the alternating supply current until the negative charge on the control electrode M has decreased to a=proper value by 1e on through the photoelectric cell or other input impedance, and the grid regains its control on the discharge.

As the rate of the decrease of the grid potenor the photoelectric current or the impedance of the cell 26 but also upon the 'size of the capacity of the condenser to be discharged, an adaptation and adiustment of the sensitivity in accorce with the prevailing conditions may also be scanned by adjusting the value of the capacity of the condenser 2E. r this purpose condenser 2b, in 2, has been shoto be variable.

The applicability of the invention, as is obvious, is not limited to the control of gaseous discharge relays by photoelectric cells only, as shown in the embodimentsoi the drawing. The

'sulwtituted by a y other discharge device, .such

as an electronic tube, an ionization chamber,

and the like, or by any input impedance, such as Thus, the system as described in Figures land 2 may be usedior theatre lighting or motor control, etc. by substituting a finely controllable. resistance fan the 7Q photoelectric cell ll whereby large output current-in the translating device it (Figure 1) or 22 (Figure 2) may be gradually and contin- By substituting usinga of suit- M.

able ohmic range in such a manner that the discharge time through the grid leak or photoelectric cell as represented by the slanting portion of the curve 33 according to Figure 3 is extended to cover more than one cycle of the operating current the number of operating or discharge periods is reduced as compared to the frequency of the operating current. In this case the device may serve as a frequency reducing system for producing a lower, frequency from currents of higher frequency.

In order to still further illustrate the numerous applications .of the invention, we have shown a special embodiment -of a practical control system which will be described in connection with Figure 4 of the drawing, referring to the an electric rnotor 33 serving to directly operate a control mechanism and a switch 34. The control electrode of the discharge tube 3| is negatively biased by means of a battery or other potential source 35' in such a manner that the ignition potential 0! this tube is higher than the operating potential. An induction coil 35 is includedin the grid circuit of the tube. Thecontrol electrode of the discharge tube 32 is connected with the cathode through a high ohmic resistance 36 in such a manner that the ignition potential of this tube is very low under normal conditions. An inductance coil 31, in series with the, condenser 33, is furthermore connected between the control electrode and the cathode of the tube 32, in accordance with the ,distance from each other.

invention, serving for imparting a control potential to the control electrode.

The coils 35 and 31 are arranged at a certain A coil 39 is urthermore arranged on the vehicle or moving object, and a current of medium or high frequency constantly passed through this coil. Thus, if the coil 39 passes the stationary coils 35 and 31 in the direction of the arrow 40, it will induce at first a potential difference on the grid of the tube 3|in opposite direction to the bias- .ing battery voltage 35, whereby the discharge is started. This will at once cause in turn a discharge of. the second tube 32, thus setting in operation the servo-motor 33 operating the desired control mechanism. As soon as the latter .arrives in its final position, it will open contacts 38, resulting in an attraction of electrons from the discharge emission, and a consequent increase of the ignition potential of this tube beyond the operating voltage. If, then in the manner above described, tube 3| is opened for a short period, a breakdown is thus prevented.

The negative charge of the control electrode of tube 32 will then gradually leak off through the resistance 35, thus returning the system to its initial operating state after the lapse of several series arrangement of a condenser and an into the othervplate of said' condenser in a period seconds. This system may serve for counting, trafilc control or similar purposes, as is understood, where a record or operation of a control mechanism, such as for example the lowering of road barriers at a railroad crossing is desired '5 for vehicles or other objects moving in a predetermined direction.

;From the above it is seen that our invention in its broadest aspects contemplates novel means and a method for operating gas discharge tubes comprising an electron emitting cathode, anode and a control electrode. According to the underlying principle operation of the in-- vention as seen from the above, a periodic ignition and extinction -of the discharge through the tube is eflected with the provision of means, such as a combination of condenser and leak resistance, for storing a negative impulse charge on-the control electrode during the extinction periods andfor consecutively allowing said 20 charge .to leak of! through a variable impedance in accordance with the variation of an input or. controlling condition in such a manner as to secure corresponding variations of the average output current flowing through the tube by timing the starting of the discharge during the ignition periods.

We claim: 1. An electricalsystem comprising a gaseous discharge tube having a sealed envelope filled with a gaseous atmosphere; a pair of main electrodes therein, one of said electrodes being an electron emitting electrode; a third electrode for controlling the discharge current; an output circuit including a source of direct current operating potential for, said main electrodes; a controlling circuit connected between said control electrode and said electron emitting electrode including a series condenser having one plate connected to said control electrode; an oscillatory circuit connected between said main electrodes and coupled with said control circuit; and an impedance varying in accordance with a controlling magnitude connected to said control electrode and the positive terminal of said direct current source to serve as a leak resistance.

2-. In an electrical system as described in claim 1, in which said oscillatory circuit consists of a ductance coil; a further inductance coil in said control circuit coupled therewith; and means for regulating the phase of the induced. current in said control circuit comprising a variable condenser connected in parallel across said further inductance.

3. An'electrical system, comprising a gaseous discharge tube having a cathode, anode and a grid electrode; a condenser having one plate connected to said control electrode; a source of alternating current connected between said cathode and anode for periodically starting and stopping an ionic discharge through said tube; means for applying a peaked potential impulse of substantially lesser duration than the discharge periods of said tube and in substantially the same phase relation as the corresponding potential applied to said anode for storing a corresponding negative discharge preventing potential on said first mentioned condenser plate; and a leak resistance connected to said grid adapted to vary in accordance with .a controlling magnitude for timing the starting instants of the discharge. a v

2,049,647" 4. In a system as described in claim 3, in

which said leak resistance is comprised of a photoelectric device, and a translating device inserted in the anode output circuit of said discharge relay. I

5. In combination, a discharge device comprising an envelope; an inert gas atmosphere therein, a cathode, an anode and a grid therein; an alternating anode potential source connected between said anode and cathode for periodically starting and stopping an ionic discharge through said tube for producing alternate operating and non-operating cycles of said tube; further means for applying peaked negative potential impulses to said control element of substantially lesser duration than and prior to the beginning of the conducting cycles; means for storing the peak negative potential at said grid and means for gradually removing said stored potential at vari-' able rates in accordance with variations of a physical controlling magnitude for timing the starting of the discharge at variable instants during the conducting cycles, and a translating device connected in the anode circuit of said tube.

6. The method of gradually varying the output current ofa vapor discharge device in ac cordance with variations of a controlling magnitude which consists in periodically alternately starting and stopping an produce periodic conducting and non-conducting periods; and controlling the average discharge current by correspondingly periodically variably delaying the starting of the discharge by subjecting it to a short discharge preventing peaked potential impulse of substantially lesser duration than and prior. to the conducting periods; storing said discharge preventing poionic 1 dischargethrough said device at a definite frequency to tential; and gradually removing said stored potential during variable time periods in accordance with variations of a controlling magnitude.

7. The method of gradually varying the, output current of a vapor discharge device having a cathode, an anode and a control element in accordance with variationsof a controllingmagnitude consisting f in periodically producing alternate conducting and non-conducting periods and varying the average discharge current flow by electrostatically delaying the starting of the discharge during the conducting periods for in; an alternating current source connected'to said cathode and anode for periodically starting and stopping an ionic discharge through said .tube;'- a condenser having one electrode connected to said control element;,a highly saturable iron core transformer-connected between the other electrode of said condenser and said cathode for applying a peaked positive potential impulse to said condenser prior to the discharge periods of said tube and storing said potential at said grid; and a leak impedance varying in accordance with a physical controlling magnitude' connected to said control element.

' HEINRICH -H.' GEFFCKEN.

HANS R. RICHTER.

.cathode and anode and a control element there- 

